1. Field of the Invention
This invention relates to a heat-up/cool-down bimetal timer for an electric toaster, and more particularly, to an improved fastener for a calibration adjustment screw that is not readily deformed during adjustment of the screw.
2. Description of the Prior Art
In a heat-up/cool-down bimetal timer disclosed in a prior U.S. Pat. No. 3,684,860 issued Aug. 15, 1972 and assigned to the same assignee as the instant invention, there is disclosed a heat-up/cool-down bimetal timer for timing the toasting cycle of an electric toaster wherein a calibration screw 128 functions as a contact that is engaged by a moveable contact 124 at the end of a heat-up/cool-down bimetal blade 120 for signalling the termination of the bimetal cool-down cycle when the contact 124 at the end of the bimetal abuts the contact on the end of the adjusting screw. As shown more particularly in FIGS. 10, 11, and 12 of the patent, it can be appreciated that the adjusting screw 126 may be adjusted during manufacture of the heat-up/cool-down bimetal and that the timer cycled may be shortened by moving the end of the screw 128 closer to the contact 124 at the end of the bimetal blade 120 of the heat-up/cool-down bimetal timer. Manufacturing adjustment of the screw may be achieved by having automated screw driving equipment move into engagement with the head of the screw to rotate the screw clockwise to move the contact tip of the screw closer to contact 124. After the desired adjustment, the automated equipment is removed from the head of the screw and the fastener through which the screw is threaded holds the screw in its adjusted position.
As illustrated in FIG. 10 of the patent, the fastener comprises a strip of sheet metal that is secured to a bracket 186. The screw 126-128 is threaded through an aperture that is formed in the sheet metal fastener and is held in adjusted position by means of spring fingers that depend downwardly from the fastener toward the aperture. The principal surface of the sheet metal fastener is arranged generally perpendicular to the screw and to forces that automated equipment might apply to the head of the screw as it is moved into engagement with the head of the screw. Too strong forces would tend to bend the fastener about its connection with the bracket 186.
Our invention is concerned with such calibration adjusting screw fasteners, and more particularly, to a unique sheet metal fastener which is not readily deformed while the adjusting screw is being adjusted.
Accordingly, it is a particular object of our invention to provide an improved calibration adjustment screw and fastener for a heat-up/cool-down bimetal timer which may be readily manufactured of relatively few parts. It is another object of our invention to provide an improved calibration screw and fastener for precisely locating the screw and maintaining the screw in good alignment with a contact with which it cooperates.
It is also an object of our invention to provide a fastener that has a constant frictional drag to hold the screw in its adjusted position. It is a still further object of our invention to provide a fastener and adjustment screw which may be adjusted by automated manufacturing equipment and lends itself to less critical methods of manufacture and tolerances as compared to other known constructions.